Harmonic generator



Dem 1943- r J. c. TELLIER ETAL 2,455,824

HARMONIC GENERATOR Filed NOV. 30, 1944 F/G. 1. P/w/P 4/?7 INVENTORS IOJEPH C. TELL/ER HARRY h. A/ILSON J12 be too low."

of Fig. 1 altered to incorporate two modifications in accordance with our invention-which modifications have resulted in increasing the harmonic voltage output many times.

The more important of the two modifications consists addition of a coiljfiwhich, y reason of its di str-ibuted" capacity,: ,is self reso narit to the desired harmonic. For theexample stated, coil 26 would be made self-resonant to 56 mega;

cycles. Of course, the self-resonant coil 26 could 4 case, screen grid 40 is grounded for radio frequency through a capacitor 41.

The invention is, of course, susceptible to furthere modifications and is not limited to the embodiments shown.

In the appended claims, the term parallel- 'resonant, used with reference to 'a coil, refers both to self-resonance of the coil and to resonance thereof by virtue of a parallel-connected be replaced by a coil and condenser -connected.

in parallel and tuned to thedesired harmonic.

The major cause of thedifff ic1ilty'which we experienced with the arrangement"of Figfl proved to be the low impedance at'the-d'e'sir e'd harmonic frequency between grid and cathode which was offered by capacitor l6. Byinterew".

posing coil 26, which is preferably self resonant to the desired harmonic, the admittance 'o'f'the external grid-cathode path, at the harmonic frewas' decreased 'to a value approximating '20, but at the same 26 at the fundamental quency, that of grid-leak resistor time, the influence of coil frequency provedto'be negligiblel Manifestly, it is to be expectedthat'the' im- 5,

'prov'ement to: be realized'from' the addition of coil 26 will-be more pronounced at'higherharmonies than at lower harmonics, since the deficiency of the arrangement of Fig;.1:is greater at the higher harmonics. 4 The second modificationincorporatedin Fig. 2 consists in the substitution of a coil. 21 in. place of resistor 2L. Coil 21 ismade-self-resonant to the fundamental frequency-whichis to say, '7

megacycles-andit can, of course, be replacedbyz a coil'and condenser connecte yiin parallel and tuned to the fundamental frequency.

Since coil 21 is of very high impedance atthe fundamental frequency it zhas no appreciable shunting effect on thetankgcircuit condenser 15- at that frequency; andsinee, .byvirtue of its distributed capacity, it offers extremely lowimpedance at the high harmonicsought to be developed, itv provides a low impedance pathfiiom cathode to ground at said harmonic frequency. Moreover, by utilizing coil 21 in .place' of resistor 2! an additionalgain is realized in thatthe full plate voltage is applied tothe tube.

Fig. 3 illustrates howour invention may be applied where the oscillator is of the Hartley type Here the osci1latortank .cir'cuit' 28 comprises a piezo crystal 29 and the usual l-lartley tuning inductance 3E1. The'pentode 3| may be identical with those indicated in Figs. 1 and 2 and its cathode 32 is connected to an intermediate point on. coil 36. Negative bias for grid 33 is obtained by means of grid condenser 34' and grid leak resisto'r35.

In series with coil 30 and included in the gridcathode external path i'sa coil 36 which is'self-,,

resonant to the desired harmonic frequencyand serves the same purpose as coil 26 in 'Fig. 2.

Coil 30 has so much distributed capacity that, in the absence of coil 35, the grid-cathode external impedance at the harmonic frequency would;

Coil 31 is made sel -resonant to thefundamental frequency and-functions in the same wayas coil 2'! of Fig. 2., I

Of course, either orboth of coils 36and 31,-

may be replaced by a .coil and cpndenser,,as

previously mentioned. i I

The :piatecircuit 3.8 of tube 3! includes ,a

tank circuit 39 whichi'stundtb the desired harmonic and corresponds in ,all respects ,totank;

circuit 25 of Figs. 1 and 2. 'As in the previous condenser.

Weclaim: 1. In a harmonic-frequency wave generator, a

i fundamental-frequency oscillator comprising a vacuurn tube having a cathode, a grid, and an electrode functioning as an anode, said oscillator also including a fundamental-frequency-determining network a portion thereof being comprised of a tuned network which is parallel-resoham to a desired harmonic frequency, a path external of said tube interconnecting said grid and cathode, said'path comprisinga'portion of said fundamental frequency-determining network and including said tuned network which is 'parallel-resonant'to the desired harmonic .frequen'cy, said path, exclusive of said tuned network, being of low. impedance. to the desired "harmonic frequency,= means coupling saidqoscillator anode and said fundamental-frequencydetermining network, and anioutput circuit elec- 3 tron-coupled to'said oscillator throughthe, spacepath-of said tube, saidoutput circuit being tuned to said desired harmonic frequency.

- 2. In a harmonic-frequency wave generator, a

, fundamental-frequency oscillator comprising a vacuum, tube having afcathode, a grid, andan electrode functioning as .an anode, said oscillator also including a fundamental-frequency determining network a portion thereof being com- -.prised of a tuned network which is parallel-reso- 40' ...ternal of; said tube interconnecting said grid and nant to a desired harmonic frequency, a path excathode, said path: comprising ,aportion of said fundamental frequency -determining network and including said tuned network which is parallel-resonant to the desired harmonic frequency, .said path, exclusiveof saidtuned network, being of ,lowimpedance tojthe desiredjharrnonic "frequency, means coupling said oscillator anode and frequency, and I f plying space current to" said tube, said circuit inham to the cillator also including f oscillator through the said fundamental frequency-determining net- ,tal shunted by a series branchcomprised of a first capacitor, a second capacitor and a tuned network, said tuned network being parallel-resonant to a desired harmonic frequency, said cathode being connected to: said tank circuit at a point between said first and second capacitors, a path interconnecting said cathode and grid, said path including said tuned network and said first'capacitor'only excluding saidcrystal, means coupling said oscillator anode mental-frequency-determining.

and said fund atank circuit, and an output circuit electron-coupled to said oscillator through the space-path-of said tube, said output circuit being tuned to said desired harmonic frequency, and a direct current circuit for supplying space current to said tube.

In a harmonic-frequency wave generator, a fundamental-frequency oscillator comprising a shunted by a series branch comprised of a main inductance coil and a tuned network parallelresonant to a desired harmonic frequency, said cathode being connected to an intermediate point in said main inductance coil, a path interconnecting said cathode and grid, said path including a portion of said main inductance coil in series with said tuned network which is parallel-resonant to the desired harmonic, means coupling said oscillator anode and said fundamental-frequency-determining tank circuit, an output circuit electron-coupled to said oscillator through the space-path of said tube, said output circuit being tuned to said desired harmonic frequency, and a direct-current circuit for supplying space current to said tube.

5. In a harmonic-frequency wave generator as claimed in claim 1, characterized in that said tuned network which is parallel-resonant to said desired harmonic frequency comprises an inductance coil which resonates with the inherent distributed capacitance.

6. In a harmonic-frequency wave generator as claimed in claim 2, characterized in that said tuned network which is parallel-resonant to said desired harmonic frequency comprises'an inductance coil which resonates with the inherent distributedcapacitance.

7. In a harmonic-frequency Wave generator as claimed in claim 3, characterized in that said direct-current circuit includes a cathode-coupled tuned network which shunts said second capacitor and is substantially parallel-resonant to said fundamental frequency.

8. In a harmonic-frequency wave generator as claimed'in claim 4, characterized in that said direct-current circuit includes a cathode-coupled tuned network which shunts the portion of said main inductance coil not included in said cathode-to-grid path, said last-named network being substantially parallel-resonant to said fundamental frequency.

9. In a harmonic-frequency wave generator; a fundamental-frequency oscillator comprising a vacuum tube having a cathode, a grid, and an electrode functioning as an anode, said oscillator also including a fundamental-frequency-determining network comprised of a piezo-crystal and.

a series branch shunting said crystal, said series branch being comprised of a first reactance, a second reactance of like sign and a tuned network substantially parallel-resonant to a desired harmonic frequency, said piezo-crystal being .adapted to resonate only at a frequency in the vicinity of said fundamental frequency, a path external of said tube interconnecting said grid and cathode, said path comprising said first reactance and said tuned network and excluding said second reactance, a path external of said tube coupling said oscillator-anode and said fundamental-frequency-detennining network; an output circuit electron-coupled to said oscillator through the space-path of said tube, said output circuit including a tuned circuit resonant to said desired harmonic frequency; and a directcurrent path for supplying space current to said tube.

10. In a harmonic-frequency wave generator as claimed in claim 9, characterized in that said direct-current path includes a cathode-coupled tuned circuit which shunts said second reactance of said fundamental-frequency-determining network, said last-named network being substantially parallel-resonant to said fundamental frequency.

11. In a harmonic-frequency wave generator; a fundamental-frequency oscillator comprising a vacuum tube having a cathode, grid, and an electrode functioning as an anode, said oscillator also including a fundamental-frequency-determining network comprised of a piezo-crystal and a series branch shunting said crystal, said series branch being comprised of first, second and third reactances, said first and second reactances being of relatively low impedance at said fundamental frequency and also at harmonic frequencies, said third reactance being of relatively low impedance at said fundamental frequency but of high impedance at harmonic frequencies, a path external of said tube interconnecting said grid and cathode, said path comprising said first and third reactances but excluding said second reactance, a path external of said tube coupling said oscillator-anode and said fundamental-frequency-determining network; an output circuit including a tuned circuit resonant to a preselected harmonic frequency; and a direct-current path for supplying space current to said tube.

12. In a harmonic-frequency wave generator as claimed in claim 11, characterized in that said direct-current path includes a cathode-coupled reactance which shunts said second reactance of said fundamental-frequency-determining network, said cathode-ccupled reactance being of high impedance to said fundamental frequency.

JOSEPH c. TELLIER. HARRY H. WILSON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,719,521 Schaffer July 2, 1929 1,982,916 Kummerer Dec. 4, 1934 2,013,806 Osnos Sept. 10, 1935 2,168,924 Dow Aug. 8, 1939 2,256,931 Wolfskill Sept. 23, 1941 2,313,071 Hodgson Mar. 9, 1943 

